iSixSigma

Tim Chambers

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  • #59767

    Tim Chambers
    Member

    Here we talk a lot about the two different styles of poke yoke – I don’t know whether there are official terms for them, the indicators – colour coding, shadow boards, tick boxes, and the physically preventative – jigs, pins, barriers etc. Obviously the ‘harder’ solution being physically preventative.
    With this X ray idea, surely we should/could generate a physical barrier ? I’m not fully aware of the scenario – but what about some type of cut-out in the film and key for this to fit into on the light board ? Or – if the film is always held in a gripper – having left/right hand teeth so the film will not be held the wrong way round.

    What about going a little further and having the film polarised ? – polarise it diagonally, and have all the light boards similarly polarised – then with the film the wrong way round it will appear totally black – thus ‘automatically’ preventing the film from being read. Wether this can be done with the film I’m not sure (any takers ?) – creating poke yokes for the generation of the film would also be required of course. (I wonder if this idea had been patented ?)

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    #71594

    Tim Chambers
    Member

    Here we talk a lot about the two different styles of poke yoke – I don’t know whether there are official terms for them, the indicators – colour coding, shadow boards, tick boxes, and the physically preventative – jigs, pins, barriers etc. Obviously the ‘harder’ solution being physically preventative.
    With this X ray idea, surely we should/could generate a physical barrier ? I’m not fully aware of the scenario – but what about some type of cut-out in the film and key for this to fit into on the light board ? Or – if the film is always held in a gripper – having left/right hand teeth so the film will not be held the wrong way round.

    What about going a little further and having the film polarised ? – polarise it diagonally, and have all the light boards similarly polarised – then with the film the wrong way round it will appear totally black – thus ‘automatically’ preventing the film from being read. Wether this can be done with the film I’m not sure (any takers ?) – creating poke yokes for the generation of the film would also be required of course. (I wonder if this idea had been patented ?)

    0
    #70737

    Tim Chambers
    Member

    To be honest – I much prefer the use of Cp & Cpk terms (in conjunction) to describe a process in relation to it’s specification, a completely unambigous method (as long as everyone uses 3 deviations).
    I don’t like negative sigma, I prefer conversion of  %good (to sepc limits) to sigma level; using +NORSINV() in Excel for example.

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    #70713

    Tim Chambers
    Member

    I don’t agree you can have negative sigma, I don’t agree you can have negative Cp, I do agree you can have negative Cpk.
    I think this is all driven by how you calculate sigma levels, if calculated from simple 3 x Cpk values, it is obvious how negatives have been generated (i.e. process average outside spec. limits). If generated from absolute inside spec. – outside spec. standpoint you should not go below zero, you could be at zero, but not below.
    Taking 1.5 sigma away at these low levels for a coversion to long term results is also false, 1.5 being a simplistic ‘catch-all’ figure, different for each process. For example, as sigma levels approached, say, 0.5, the long term effect maybe something like 0.2 sigma, whatever; it would be less than 0.5 – measure it.

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Viewing 4 posts - 1 through 4 (of 4 total)